Online Numerical Recipes
An online version of the Numerical Recipes book has been available for a while now, but it has fairly recently moved, and the publisher has also placed the new (third) edition online. So I thought this was a good time to post out the current URLs for those information junkies out there, as it is a good reference to have bookmarked.
The second edition is available here (both C and Fortran): https://www.nrbook.com/a/
The new third edition release is here: https://www.nrbook.com/nr3/
“Only with this third edition, however, have we incorporated a substantial amount (several hundred pages!) of completely new material”
For an index of the available 3rd edition code routines, check out https://www.nr.com/routines/